noip.com is one of the few dynamic DNS free
services that are reliable to use. If you have, like in my situation, a
RaspberryPi connected to your home DSL and you want it to be always
reachable without knowing the current IP address (the IP could change if
you have a normal DSL service at home), you need a dynamic DNS service.

To update the noip.com one you just need ddclient a tool that is
available in Raspbian/Debian repository. You can install it with this
command:

That's all! Please remember that noip.com free accounts have a
limitation: they need to be confirmed every 30 days (you will
receive an email and you need to click on the link contained to update
your DNS).